js/encoding/DataUtils.js

/**
 * This class contains utilities to help parse the data
 * author: Meki Cheraoui, Jeff Thompson
 * See COPYING for copyright and distribution information.
 */
 
/**
 * A DataUtils has static methods for converting data.
 * @constructor
 */
var DataUtils = function DataUtils(){
};


/*
 * NOTE THIS IS CURRENTLY NOT BEING USED
 * 
 */

DataUtils.keyStr = "ABCDEFGHIJKLMNOP" +
               "QRSTUVWXYZabcdef" +
               "ghijklmnopqrstuv" +
               "wxyz0123456789+/" +
               "=";

               
/**
 * Raw String to Base 64
 */
DataUtils.stringtoBase64=function stringtoBase64(input) {
     //input = escape(input);
     var output = "";
     var chr1, chr2, chr3 = "";
     var enc1, enc2, enc3, enc4 = "";
     var i = 0;

     do {
        chr1 = input.charCodeAt(i++);
        chr2 = input.charCodeAt(i++);
        chr3 = input.charCodeAt(i++);

        enc1 = chr1 >> 2;
        enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
        enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
        enc4 = chr3 & 63;

        if (isNaN(chr2)) {
           enc3 = enc4 = 64;
        } else if (isNaN(chr3)) {
           enc4 = 64;
        }

        output = output +
           DataUtils.keyStr.charAt(enc1) +
           DataUtils.keyStr.charAt(enc2) +
           DataUtils.keyStr.charAt(enc3) +
           DataUtils.keyStr.charAt(enc4);
        chr1 = chr2 = chr3 = "";
        enc1 = enc2 = enc3 = enc4 = "";
     } while (i < input.length);

     return output;
  }

/**
 * Base 64 to Raw String 
 */
DataUtils.base64toString = function base64toString(input) {
     var output = "";
     var chr1, chr2, chr3 = "";
     var enc1, enc2, enc3, enc4 = "";
     var i = 0;

     // remove all characters that are not A-Z, a-z, 0-9, +, /, or =
     var base64test = /[^A-Za-z0-9\+\/\=]/g;
     /* Test for invalid characters. */
     if (base64test.exec(input)) {
        alert("There were invalid base64 characters in the input text.\n" +
              "Valid base64 characters are A-Z, a-z, 0-9, '+', '/',and '='\n" +
              "Expect errors in decoding.");
     }
     
     input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

     do {
        enc1 = DataUtils.keyStr.indexOf(input.charAt(i++));
        enc2 = DataUtils.keyStr.indexOf(input.charAt(i++));
        enc3 = DataUtils.keyStr.indexOf(input.charAt(i++));
        enc4 = DataUtils.keyStr.indexOf(input.charAt(i++));

        chr1 = (enc1 << 2) | (enc2 >> 4);
        chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
        chr3 = ((enc3 & 3) << 6) | enc4;

        output = output + String.fromCharCode(chr1);

        if (enc3 != 64) {
           output = output + String.fromCharCode(chr2);
        }
        if (enc4 != 64) {
           output = output + String.fromCharCode(chr3);
        }

        chr1 = chr2 = chr3 = "";
        enc1 = enc2 = enc3 = enc4 = "";

     } while (i < input.length);

     return output;
  };

/**
 * Uint8Array to Hex String
 */
//http://ejohn.org/blog/numbers-hex-and-colors/
DataUtils.toHex = function(args){
	if (LOG>4) console.log('ABOUT TO CONVERT '+ args);
	//console.log(args);
  	var ret = "";
  	for ( var i = 0; i < args.length; i++ )
    	ret += (args[i] < 16 ? "0" : "") + args[i].toString(16);
  	if (LOG>4) console.log('Converted to: ' + ret);
  	return ret; //.toUpperCase();
}

/**
 * Raw string to hex string.
 */
DataUtils.stringToHex = function(args){
	var ret = "";
	for (var i = 0; i < args.length; ++i) {
		var value = args.charCodeAt(i);
		ret += (value < 16 ? "0" : "") + value.toString(16);
	}
	return ret;
}

/**
 * Uint8Array to raw string.
 */
DataUtils.toString = function(args){
  //console.log(arguments);
  var ret = "";
  for ( var i = 0; i < args.length; i++ )
    ret += String.fromCharCode(args[i]);
  return ret;
}

/**
 * Hex String to Uint8Array.
 */
DataUtils.toNumbers = function(str) {
	if (typeof str == 'string') {
		var ret = new Uint8Array(Math.floor(str.length / 2));
        var i = 0;
		str.replace(/(..)/g, function(str) {
		    ret[i++] = parseInt(str, 16);
		});
		return ret;
    }
}

/**
 * Hex String to raw string.
 */
DataUtils.hexToRawString = function(str) {
    if(typeof str =='string') {
		var ret = "";
		str.replace(/(..)/g, function(s) {
			ret += String.fromCharCode(parseInt(s, 16));
		});
		return ret;
    }
}

/**
 * Raw String to Uint8Array.
 */
DataUtils.toNumbersFromString = function(str) {
	var bytes = new Uint8Array(str.length);
	for(var i=0;i<str.length;i++)
		bytes[i] = str.charCodeAt(i);
	return bytes;
}

/**
 * Encode str as utf8 and return as Uint8Array.
 * TODO: Use TextEncoder when available.
 */
DataUtils.stringToUtf8Array = function(str) {
    return DataUtils.toNumbersFromString(str2rstr_utf8(str));
}

/**
 * arrays is an array of Uint8Array. Return a new Uint8Array which is the concatenation of all.
 */
DataUtils.concatArrays = function(arrays) {
    var totalLength = 0;
	for (var i = 0; i < arrays.length; ++i)
        totalLength += arrays[i].length;
    
    var result = new Uint8Array(totalLength);
    var offset = 0;
	for (var i = 0; i < arrays.length; ++i) {
        result.set(arrays[i], offset);
        offset += arrays[i].length;
    }
    return result;
    
}
 
// TODO: Take Uint8Array and use TextDecoder when available.
DataUtils.decodeUtf8 = function (utftext) {
		var string = "";
		var i = 0;
		var c = 0;
        var c1 = 0;
        var c2 = 0;
 
		while ( i < utftext.length ) {
 
			c = utftext.charCodeAt(i);
 
			if (c < 128) {
				string += String.fromCharCode(c);
				i++;
			}
			else if((c > 191) && (c < 224)) {
				c2 = utftext.charCodeAt(i+1);
				string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
				i += 2;
			}
			else {
				c2 = utftext.charCodeAt(i+1);
				var c3 = utftext.charCodeAt(i+2);
				string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
				i += 3;
			}
 
		}
 
		return string;
	};

/**
 * Return true if a1 and a2 are the same length with equal elements.
 */
DataUtils.arraysEqual = function(a1, a2){
    if (a1.length != a2.length)
        return false;
    
    for (var i = 0; i < a1.length; ++i) {
        if (a1[i] != a2[i])
            return false;
    }

    return true;
};

/**
 * Convert the big endian Uint8Array to an unsigned int.
 * Don't check for overflow.
 */
DataUtils.bigEndianToUnsignedInt = function(bytes) {
    var result = 0;
    for (var i = 0; i < bytes.length; ++i) {
        result <<= 8;
        result += bytes[i];
    }
    return result;
};

/**
 * Convert the int value to a new big endian Uint8Array and return.
 * If value is 0 or negative, return Uint8Array(0). 
 */
DataUtils.nonNegativeIntToBigEndian = function(value) {
    value = Math.round(value);
    if (value <= 0)
        return new Uint8Array(0);
    
    // Assume value is not over 64 bits.
    var size = 8;
    var result = new Uint8Array(size);
    var i = 0;
    while (value != 0) {
        ++i;
        result[size - i] = value & 0xff;
        value >>= 8;
    }
    return result.subarray(size - i, size);
};

/**
 * Modify array to randomly shuffle the elements.
 */
DataUtils.shuffle = function(array) {
    for (var i = array.length - 1; i >= 1; --i) {
        // j is from 0 to i.
        var j = Math.floor(Math.random() * (i + 1));
        var temp = array[i];
        array[i] = array[j];
        array[j] = temp;
    }
};